Field of the Invention
The invention relates to a device for decollating flat objects from a stack, in particular objects individually separated from one another in the stack by interlayers, preferably printing plates.
For individually handling flat objects that are stacked on top of one another, the objects first must be decollated and then fed individually one after the other into a processing machine. In particular, printing plates must be introduced individually into a printing plate exposure machine for purposes of exposure. While decollating may be done manually, an automatic loading device (loader) is preferred. Such a device can be connected or docked before a printing plate exposure machine. A stack of printing plates to be exposed is fed into the loading device and the loading device should have available to it a decollating device of the generic category identified at the outset in order to allow automatic decollation and loading.
However, the decollation operation and the loading operation can be disturbed and adversely affect or impede the subsequent machining whenever a plurality of objects adhere to one another or an object adheres to an interlayer. Interlayers are used to separate an object from a succeeding or preceding object in the stack. In the case of printing plates, sheets of paper can be used as interlayers for purposes of separation. It is also possible that such interlayers have not been provided, in individual cases, are inadvertently missing, or are present in a double layer.
It is accordingly an object of the invention to provide a device for decollating flat objects, preferably printing plates, that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that ensures that one object and one object alone is taken from the stack and made available for any further handling.
With the objects of the invention in view, there is also provided a device including a lifting device and a separating device. The lifting device is for lifting one of the objects from the stack. The separating device is for separating an article possibly adhered to the underside of the lifted object from the lifted object.
This task is solved according to the invention by a lifting device for lifting the object from the stack and a separating device for separating any article possibly adhering to the underside of the lifted object from the lifted object. Typically, the article that is adhering is a second object or an interlayer.
In the problem area of malfunctions in object decollation indicated merely in outline above, a number of cases may be distinguished all of which must be reliably overcome by the device according to the invention.
First, there may be the desired situation in which from the outset only one object is seized and removed from the stack. No special measures need be provided for this regular case. According to the invention, the object is lifted by the lifting device and made available on its own.
In an undesired situation, a second object might adhere to the underside of the upper object in the stack. The upper object might then be lifted together with the second object adhering thereto. However, this problem could be solved by the lifting action itself in that the force of gravity acts on the lower object and the latter falls by itself back onto the stack, especially according to a refinement of the invention when a suction element lifts the object by acting only from above on the upper object. Otherwise, if necessary, the lower object may be actively separated off using the separating device provided according to the invention.
In another case, an interlayer may adhere to the underside of the lifted object. This too could fall back again by itself onto the stack due to the force of gravity or if it is separated from the object before the object is made available by the separating device according to the invention.
As for the rest, it may be regarded as regular and specified for the device according to the invention that an object and an interlayer each alternate in the stack. Therefore, on each second lifting action of the lifting device, an object is lifted. Therebetween, in each case, in each second lifting action of the lifting device, an intermediate stacking unit is lifted. In the second lifting action, an object may be made available in each case for further handling. Each intermediate stacking unit, in each case, may be transported away for disposal or recycling. Thus, for this purpose, the device according to the invention could operate at twice as high a working rhythm as a following processing machine. Moreover, the same lifting device could be used for the objects and the interlayers.
According to the invention, the lifting device preferably seizes the object to be lifted only in the region of an edge. This protects the object as much as possible. In this manner, in the case of a printing plate for example, the area to be imprinted is not adversely affected. Rather, the printing plate is seized, for example, only in the peripheral region, which in any case is provided only for stamping.
The separating device according to the invention can be constructed as a type of peeling element, similar to a doctor knife for example, wherein such a separating element can be disposed in stationary manner, for example as an edge of a support table. Then, the lifted object is conveyed over the edge so that any interlayer possibly attached on the underside is held back and peeled off. As a result, the object is freed of this interlayer, which can fall into a disposal container.
Alternatively, the separating device may also be of more active construction. In another alternative, a plurality of different separating devices may also be provided.
The single separating device can by way of example be of similar construction to the lifting device and in particular include suction elements. The lifting device can then grip the object on the upper side and in similar fashion the separating device can seize any interlayer or second object adhering on the underside and the lifting device and the separating device then pull the object and the interlayer or the second object apart to separate them. If the object and the interlayer are generally regarded as an article, a guide system for the orderly pick-up and transport away of an article can be provided according to a development of the invention.
Preferably, the separating device possesses a carrier element that also serves as a movable transport support for the object. Thus, the carrier element can transport an object onwards just while an interlayer can be transported away for disposal.
Advantageously, the transport support can be of flexible construction, preferably shaped like a shutter. The transport path for an object can then extend in a level manner on an upper plane and the peeling element can project into the region of transfer of the object from the transport support to a support table. In contrast, an interlayer is transported downwards ahead of or upon reaching the peeling element by turning of the transport support so that there is a sort of switch point for objects and interlayers in the region of the peeling element.
The transport support can be part of a transport element that extends in a closed loop over diversion members. In the transport element, articles to be disposed, in particular interlayers, are carried into the region of the lower strand of the loop. There, the articles to be disposed are allowed to fall into a container. In doing so, the articles may advantageously be deposited in orderly manner so that instead of disposal, selective recycling is also possible.
Preferably, the device according to the invention includes sensor devices for monitoring and controlling the operating sequence. In particular, the sensor devices are used for deciding which alternative possible operating sequence is appropriate in a situation found by a sensor device. Thus, a first sensor recognizes whether an article is adhering to the underside of an object lifted from the stack. In doing so, the sensor also can recognize whether the adhering article is another object or an interlayer. The sensor""s recognition can be based on differing light reflection properties of these possible articles. Thus, the sensors distinguish between the cases referred to above: that is, whether an already decollated object is being made available, whether an interlayer has been lifted in an intermediate work cycle and has to be disposed, whether an interlayer is adhering to the underside of a lifted object and must first be separated off and then disposed, or whether adhering to the object is a second object which should be separated off and fall back onto the stack.
Preferably, the device according to the invention further includes a second sensor that recognizes the supply of a decollated object and thereby initiates a further handling operation. An example of a further handling operation is the introduction of a printing plate to be exposed into an exposure machine. This second sensor may be disposed in the region of a peeling element, preferably a little behind the peeling element in the direction of transport of the object.
Additionally, in a further development of the device includes a clasp element. The clasp element acts in conjunction with the lifting device and by way of example supports an object lifted at the edge by its upper side at the edge on its underside.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a device for decollating flat objects, preferably printing plates, it is nevertheless not intended to be limited to the details shown, because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.